Casual Friday — Babbage's Difference Engine #2

Charles Babbage (1791-1871) was a computer pioneer who invented some interesting (and quite workable) mechanical computers, but never got around to actually building them. The first complete Babbage Engine was completed by the Science Museum in London in 2002, a mere 153 years “late.” Difference Engine No. 2, built faithfully to the original drawings, has 8,000 parts, weighs five tons, and is 11 feet long. More recently, the Science Museum built a second copy of the engine, which is on display at the Computer History Museum in Mountain View, California untill May of 2009. This first video is from that exhibit.

Meanwhile, Wired magazine produced a video featuring the director of the Computer History Museum’s Babbage Project:

I didn’t mention her in this post primarily because my understanding is that she didn’t work on the Difference Engine (which is in the video), but rather on Babbage’s “Analytical Engine” — which may or may not have ever been fully designed. At least, I can’t find any sources stating that the Analytical Engine reached a detailed design stage, unlike the Difference Engine.

From what I can tell, the Difference Engine isn’t really programmable — although you can change the values of its inputs. The Analytical Engine was supposed to be a fully programmable mechanical computer (i.e., with changeable algorithm and inputs), a much tougher nut to crack mechanically.